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From: Jeff LaBundy <jeff@labundy.com>
To: "Thomas Weißschuh" <linux@weissschuh.net>
Cc: Anshul Dalal <anshulusr@gmail.com>,
	linux-input@vger.kernel.org, devicetree@vger.kernel.org,
	Conor Dooley <conor+dt@kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	linux-kernel@vger.kernel.org,
	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	Conor Dooley <conor.dooley@microchip.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [PATCH v8 1/2] dt-bindings: input: bindings for Adafruit Seesaw Gamepad
Date: Sat, 25 Nov 2023 22:10:33 -0600	[thread overview]
Message-ID: <ZWLFOV/U90bhm4ow@nixie71> (raw)
In-Reply-To: <0defc0e3-dc15-459d-9e71-64f3c38a6931@t-8ch.de>

Hi Thomas and Anshul,

On Tue, Nov 14, 2023 at 08:20:46PM +0100, Thomas Weißschuh wrote:
> On 2023-11-08 06:23:35+0530, Anshul Dalal wrote:
> > Adds bindings for the Adafruit Seesaw Gamepad.
> > 
> > The gamepad functions as an i2c device with the default address of 0x50
> > and has an IRQ pin that can be enabled in the driver to allow for a rising
> > edge trigger on each button press or joystick movement.
> > 
> > Product page:
> >   https://www.adafruit.com/product/5743
> > Arduino driver:
> >   https://github.com/adafruit/Adafruit_Seesaw
> > 
> > Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> > Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> > Signed-off-by: Anshul Dalal <anshulusr@gmail.com>
> > ---

[...]

> > +properties:
> > +  compatible:
> > +    const: adafruit,seesaw-gamepad
> 
> I don't really have any clue about devicetree, but shouldn't the actual
> driver have an id-table for this "compatible"?
> 
> It had one up to v5 of the patchset.
> 
> Jeff had some comments about the OF aspect [0], but to me the state now
> seems incorrect.
> Maybe the DT can be dropped completely?
> 
> Jeff, could you advise?

My original comment was merely to say that this driver doesn't need an
entire binding because it is easily covered by trivial-devices.yaml. The
whole point of that binding is to save the trouble of writing a new file
such as this for trivial devices with this same set of common properties.

I don't feel strongly about _not_ adding a new binding for this device,
it just seems like unnecessary work for all involved. If the maintainers
do not mind, then I don't either :)

Taking things a step further, this driver really doesn't need to define
an of_device_id struct either, because I seem to recall that OF can still
bind to drivers with "compatible" strings specified in the i2c_device_id
struct.

At any rate, this version is most certainly broken because the compatible
string defined in this binding does not match SEESAW_DEVICE_NAME specified
in the driver's i2c_device_id struct, and there is no of_device_id struct.
So there is no way the driver would bind if this binding were followed in
earnest.

I see this has been addressed in the latest version, so I will take a look
at that one.

> 
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +    description:
> > +      The gamepad's IRQ pin triggers a rising edge if interrupts are enabled.
> 
> Interrupts are not supported yet by the driver.
> Should the property be there already?
> 
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    i2c {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        joystick@50 {
> > +            compatible = "adafruit,seesaw-gamepad";
> > +            reg = <0x50>;
> > +        };
> > +    };
> > -- 
> > 2.42.0
> 
> [0] https://lore.kernel.org/lkml/ZTWza+S+t+UZKlwu@nixie71/

Kind regards,
Jeff LaBundy

      parent reply	other threads:[~2023-11-26  4:10 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-08  0:53 [PATCH v8 1/2] dt-bindings: input: bindings for Adafruit Seesaw Gamepad Anshul Dalal
2023-11-08  0:53 ` [PATCH v8 2/2] input: joystick: driver " Anshul Dalal
2023-11-14 19:07   ` Thomas Weißschuh
2023-11-14 19:20 ` [PATCH v8 1/2] dt-bindings: input: bindings " Thomas Weißschuh
2023-11-14 20:32   ` Krzysztof Kozlowski
2023-11-26  4:10   ` Jeff LaBundy [this message]

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